[Clascomment] OPT-IN: Measurement of Unpolarized Cross Sections and Polarized Cross Section Differences for Deeply Virtual Compton Scattering

[Daniel Carman]

Dear Nicholas et al,

I have read through the updated draft of the DVCS paper dated Feb. 2
that was circulated for Collaboration-wide review. In general, the paper
is much improved over the previous draft that I had reviewed some time
ago. I have a number of comments on grammar/english/style for you to
work through before submission. If you have any questions, let me know.

Regards,
Daniel
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Page 1:
 - Title: Use "... Scattering on the Proton at ...".
 - Abstract:
   - Line 11. Use "... Facility using the large acceptance spectrometer CLAS.".
   - Line 14.  Use "... CLAS data and these new data are discussed ...".
 - Line 44. Use "... (GPDs).".
 - Fig. 1 caption. Add "See the text for definitions of the kinematic variables.".
 - Line 58. Use "... amplitude into hard and ...".
 - Line 67. I suggest "... $x$, $\xi$, and $t$ (see Fig. 1).".

Page 2:
- Line 72. Typo on "referred".
- Line 96. Use "... form factors, respectively [7].".
- Line 147. Use "The term ...".
- Line 151. Spurious "the" here.
- Line 154. Use "... exhibit a beam ...".
- Line 161. Use "... [18,19] and ...".

Page 3:
- Line 176. I suggest that you drop "into the experimental hall".
- Line 180. Use "... (DC) and by scintillator ...".
- Line 195. Use "... (IC) (see Fig. 4), ...".
- Line 197. Use "The IC allowed ...".
- Line 206. Use "... $t$, and $\phi$.".
- Line 209. Do not begin a new paragraph with this sentence.

Page 4:
- Line 224. Use "... $x_B$, and $t$ ...".
- Line 245. Use "... $\theta_\gamma = 0^\circ$, ...".
- Lines 262, 263, 264. As you have throughout this paper, use units with c=1.
- Line 265. Use "... they deposited ...".
- Line 270. Begin a new paragraph with the sentence "More massive ...".
- Line 274. Use "... fraction was significantly ...".
- Line 276. Use "... resolution was momentum ...".
- Line 279. Use "... that lied within ...".
- Line 280. Use "... $f_s$, which is a ...".
- Line 281. Do not begin a new paragraph here.
- Line 285. Use "Protons were identified ...".

Page 5:
- Fig. 6 caption:
  - Line 1. Use "... of momentum with the electron selection cut shown.".
 - Line 288. Use "... variables required ...".
 - Line 295. Do not begin a new paragraph here.
 - Line 296. Use "... identification included ...".
 - Line 316. Use "M{\o}ller" (check both instances of usage in this paper).
 - Line 318. Use "... small-angle ...".

Page 6:
- Line 341. Use "... $\theta_{rec}$, and $\phi_{rec}$."
- Line 342. Do not begin a new paragraph here.
- Line 342. Do not begin a new paragraph here.
- Line 348. The sentence ends here with a part missing.
- Line 350. This first paragraph is out of place here and seems "stuck in". It
  would be better at the end of this section. Also, include a scale for these
  "other" corrections.
 - Line 355. Use "... data using the ...".
 - Line 356. Use "... $p_p$, and $\theta_p$, ...".
 - Line 358. Use "... and angle as a function ...
 - Line 377. Use "... on average were less ...".
 - Line 397. Use "... measured from the kinematics of $ep ...".

Page 7:
- Line 418. Use "... for $E_X$, and ...".
- Line 431. Use "... , and $\theta_{\gamma,X}$.".
- Fig. 9 caption:
  - Line 1. Use "... for the data and the upper ...".
  - Line 4. Use "... in the EC, the distributions ...".

Page 8:
- Fig. 10 caption:
  - Line 1. Use "... (upper left) and ...".

Page 9:
- Fig. 11 caption is incomplete.

Page 10:
- Fig. 12 caption is incomplete.
- Fig. 13 caption:
  - Line 1. Use "... , and $\theta_{\gamma,X}$, and on the right for Monte ...".

Page 11:
- Line 453. Use "... reproduced the measured ...".
- Line 457. Use "... that reproduced the measured resolutions observed in CLAS."
- Line 462. Use "... $t$, and $\phi$.".
- Line 470. Use "... of Ref. [27]. These ...".
- Line 482. Use "... to a lesser accuracy ...".
- Line 486. Use "... There were also resolution effects that were ...".
- Line 494. Use "These were imperfections ... that were not ...".
- Line 502. Use "... DC and SC timing ...".
- Line 503. Use "... of the Monte Carlo and the data matched.".
- Line 506. Use "... accidental events, e.g. secondary scattering, cosmic rays,
   or other random hits, being detected.
 - Line 515. Use "... background rate, which ...".
 - Line 516. Use "... from the experiment.".
 - Line 517. Use "... efficiency was reduced by about 6\% due to the sources of
    accidental events [28].

Page 12:
- Line 621. Use "... showed good agreement.".

Page 13:
- Line 566. Use "... we imposed restrictions on ...".
- Line 577. Use "... by requiring for each part that $IM ... , $E_X$ were within ...".
- Line 587. Use "$\pi^0$" (twice on this line).
- Line 589. Use "... $t$, and $\phi$ ...".
- Line 591. Use "... it was typically ...".
- Line 593. Use "... it was on the order ...".
- Line 598. Use "... corrections were calculated and used to obtain better
   measurements of the Born ...".
 - Line 602. Use "... while the latter ...".
 - Line 606. Use "... recalling that the proton leg ...".

Page 14:
- Line 609. Use "... order contributions into account.".
- Line 610. Use "... to calculate the radiative contributions to the measured
   cross sections. This has been worked out ...".
- Line 615. Use "... we used the corrections appearing ...".
- Line 622. Use "... polarization of the incident ...".
- Line 623. Use "... then apply to th polarized ...".
- Line 624. Use "cross section".
- Fig. 16 caption. Use "Examples of radiative corrections for $ep \to e'p'\gamma$
   as a function of ..."
- Line 627. Use "... inefficiencies that were not accounted for,  such as the
   inefficiency of the SC counters and accidental backgrounds." (I think that a
   simpler discussion is more appropriate here.)
 - Line 634. Use "... (see Refs. [17,32-34]).
 - Line 637. Use "... of Ref. [35] which we denote as "standard"." (Note your
   opening quotations are not the proper ones.)
 - Fig. 17. Please improve the y-axis. One ordinate number seems to few.
 - Fig. 17 caption:
   - Line 3. Use "... of Ref. [35] is displayed as a red line. (Color online).
 - Line 645. Use "... in the resonance region, are consistent with these ...".
 - Line 653. Use "... uncertainty in this analysis are:"

Page 15:
 - Line 666. Use "... assumed a global ...".
 - Line 669. Use "... this uncertainty comprises ...".
 - Line 684. Use "... uncertainty was defined as ...".
 - Line 685. Use "... that was fit ...".
 - Line 695. Use "... on track angles at the vertex ...".
 - Line 698. "... to control knowledge of the torus field within simulations." I have
   no idea what you are trying to say here.
- Line 700. Use "The cuts we chose were momentum ...".
- Line 713. Use "... were assumed to be uncorrelated, ...".
- Line 715. Use "... 10.3\%. The overall systematic ...".
- Table I. Label second column as "Uncertainty (\%)". Also use consistent
   significant figures on the numbers in the table.
- Table I caption. Line 1. Use "... systematic uncertainties ...".
- Line 732. Use "... cross sections (see Eq. 3) were determined from the data using:"

Page 16:
- Eq. 15 should end in a period.
- Line 736. Use "They were determined ...".
- Line 741. Use "... with an uncertainty of ...".

Figs. 18 - 23: The gray error bands are nearly invisible and need to be made darker.

Figs. 18-23 caption:
- Line 1. Do not say "for the XX bin in $x_B$ and $Q^2$ ..." as this is not meaningful
  to the reader. Instead say "for the bin $x_B$=XX and $Q^2$=YY" where XX and
  YY are the average values of the kinematic variables. Then drop the "(see Fig. 5
  for bin definitions).
- Line 2. Spurious "the" here.
- Line 4. Use "statistical uncertainties and the gray bands ...".

- Figs. 21-23:
  - Line 3. Use "calculation. The bars ...".

- Note all data must be in the CLAS physics database before this paper is submitted
  and you need to include a reference in the paper.

Page 23:
- Line 761. Use "... 5.75~GeV ...".
- Line 770. Use "... lesser, energy dependence of the DVCS process. The factor is
  $x_B$, $Q^2$, and $\phi$ bin dependent, on average ...".
- Line 776. Use "... combined uncertainties of the two runs:"
- Eq. 18 should end with a comma.
- Line 777. Use "... the uncertainties in the ...".
- Line 779. This line should begin a new paragraph.
- Fig. 24 caption:
  - Line 1. Use "Histogram of uncertainty-normalized ...".
- Line 813. Use "... parameters of the models have not ...".
- Line 828. You have changed units for your angle notation. Use degrees.

Page 24:
- Line 874. Use "... staff at the Accelerator ...".

References:
- [9]. The Erratum is not formatted properly.
- [10]. Problem with the \bf here.
- [12] - [16]. Include (CLAS) in the author list.
- [24] . The CLAS paper is not a CLAS Collaboration paper.
- [25]. Use "May 2013".
- [29]. This reference does not seem complete. Is there not a CLAS-Note?
  If so, give the URL.
 - [36]. Use "... Belitsky, D. M{\u}ller, D. Niedermeier, ...".